In the following, with content we mean any content that is loaded in bursts. In particular, content may be loaded from the Internet and include at least one dynamic web page that is a web page that is prepared with fresh information (content and/or layout) for each individual viewing. In this context, the term content would refer specifically to web content.
Content is normally loaded at a terminal (the term “terminal” in the following may in particular but not necessarily refer to a mobile terminal or mobile device but it can be a desktop or a laptop or any other client device) to a browser piece by piece. First, a description of the dynamic page, such as a Hypertext Markup Language (HTML) page is loaded. The browser parses the HTML page and submits then separate requests for each piece that with the description of the dynamic page thus form the dynamic content. Currently, it is normal that a single content contains some 30-100 web objects that must be loaded, not rarely from different locations. The web objects may include images, advertisement banners, flash animations etc.
The energy consumption of a terminal that is loading a content is usually higher during the loading as compared with the terminal in its idle state, that is, when the user is reading the content that already has been loaded.
In addition, it may be that the loading itself takes longer than expected, in particular when some of the web objects cannot be retrieved. Even if the web objects could be retrieved, it may be that they must be retrieved from a remote server which is prone to increase the duration of the retrieval, especially if the retrieving is carried out over a slow link that may be a wireless link.
There are some methods that can be used to reduce energy consumption during loading of contents. In the GPRS or 3GPP standards, the wireless terminal loading a dynamic content should enter in idle state after a predetermined time has lapsed, if the requested content is not being transmitted to the terminal. Since transforming the terminal to the idle state requires some signalling, some mobile phone models are believed (cf. Network Efficiency Task Force Fast Dormancy Best Practices, GSM Association, May, 2010) to enter a sleep state aggressively in order to extend battery life and minimize network congestion but may cause signal load problems in the operator network. During browsing, the mobile device has no chance to enter idle or low power state due to HTTP requests and replies going forth and back.
RRC state transition model has remained rather unchanged through several releases, namely, Rel. 99, Rel. 05 and Rel. 06. Perala et al. present in “Theory and practice of RRC state transitions in UMTS networks”, in Proc. Fifth IEEE Broadband Wireless Access Workshop (BWA), co-located with IEEE GLOBECOM 2009, Hawaii, USA, November-December 2009 a methodology to discover RRC configuration parameters without operator involvement or cooperation, which shows how the operator network settings may differ drastically from each other.
Feng Qian et al. in “Characterizing Radio Resource Allocation for 3G Networks”, in ACM Internet Measurement Conference (IMC) 2010, Melbourne, Australia, and Feng Qian et al. in “TOP: Tail Optimization Protocol for Cellular Radio Resource Allocation” in IEEE ICNP 2010, Kyoto Japan characterize the impact of operational state machine settings and show that tail time period matching the in-activity timer value before a state demotion. During a tail time, a user equipment still occupies transmission channels and its radio power consumption is kept at the corresponding level of the state, even through there is no traffic transmitted during the period.
Signals Research Group shows in “Reducing the impact of smartphone-generated signaling traffic while increasing the battery life of the phone through the use of network optimization techniques” (May 2010) how signaling traffic generated by smartphones affects battery life and causes network congestion.
In addition to the Fast Dormancy Best Practices paper, “Understanding Smartphone Behavior in the Network” by Nokia Siemens Networks Smart labs (2011) also discusses the timer problem and shows that fast dormancy is one of the solutions, which forces devices to hop back to low power consumption state quickly to save energy and reduce traffic load.